Debate on the origin of chirality has lasted for several centuries. Lots of theories in different fields have been propounded to illustrate the possible sources. However, there were no convincing proofs could be provided. In this work, through constructing the relationship between aggregation and chirality, a significant insight was brought to explain how the chirality was generated from the achiral system. Besides, aggregation-induced circular dichroism (AICD) effect was discovered in some AIEgens decorated with amino acid or sugars and aggregation-annihilated circular dichroism (AACD) effect was reported in axially chiral systems. In AICD systems, it was proved that the chirality could transfer from chiral centers to AIEgens in the aggregate state but not solution. Meanwhile, it was concluded that the right-handed helical structures corresponded to a negative Cotton effect and vice versa. For the AACD effect, further studies suggested that the annihilation was caused by the change of twist angle within the process of aggregation.

The third- and fifth-order nonlinear optical components are extracted using z-scan under a series of irradiances for some common reference materials rhodamine B(RhB) and carbon disulfide (CS2) as well as D-A fluorophores triphenylamine-phenylaldehyde (TPA-PA) and 2diphenylamine-tetraphenylethylene-phenylaldehyde (2DPA-TPE-PA). By differentiating the third- order optical nonlinearities from high-order ones, the two-photon absorption (2PA) cross sections of RhB, TPA-PA, and 2DPA-TPE-PA estimated from z-scan are almost all consistent with those estimated from two-photon excited fluorescence, whereas the second-order refractive indices of CS2 and TPA-PA in THF solution agree with reported values in publications as well. If the z-scan curve is captured at only a single irradiance, the 2PA cross sections will probably be overestimated. As for the fifth-order optical nonlinearities, the excited-state absorption cross sections of RhB are reduced with an increase in its concentration in methanol solutions. A more comprehensive photophysical picture of the nonlinear absorption and refraction processes within these samples can be drawn from their z-scan results.

Aggregation-induced emission (AIE) has drawn continuously growing attention due to its great potential in material science and biological techniques. The AIE effect is expected to conquer the notorious aggregation-caused quenching (ACQ) encountered by conventional luminescent materials, and thus realize the high-performance organic light-emitting diodes (OLEDs) without complicated doping method. Our recent studies have demonstrated that it is feasible. The solid-state luminescent materials created by melting AIEgens with conventional chromophores that suffer from ACQ problem at the molecular levels exhibit high photoluminescence efficiency up to unity, and function efficiently as light-emitting layers in non-doped OLEDs. Tunable electroluminescence colors from blue to red and excellent efficiencies approaching theoretical limit are attained by the devices. In addition, rational modifications on AIEgens with carrier-transporting functional groups can endow the luminescent materials with not only high solid-state emission efficiencies but also good hole- or electron-transporting abilities. The non-doped bilayer OLEDs fabricated by utilizing these multifunctional materials as light-emitting and hole-transporting (electron-transporting) simultaneously afford remarkably high efficiencies. These results clearly manifest the practical utility of the AIE effect in development of active materials for OLEDs.

As opposed to most fluorophores that suffer from aggregation-caused quenching (ACQ), aggregation-induced emissive luminogens (AIEgens) possess very weak fluorescence in solution, but show strong emission upon aggregation due to restriction of intramolecular motion (RIM). Since AIEgens are often comprised of propeller-shaped structures, i.e. polyphenylsiloles or tetraphenylethylene (TPE), the attachment of chiral units has recently proven a powerful tool to fabricate chiral AIEgens exhibiting strong circularly-polarized luminescence (CPL) signal upon aggregation. Different chiral moieties lead to various assembled structures, such as helical nanoribbons, superhelical ropes, hollow and solid micro-/nanospheres. Generally, these structures exhibit enhanced chiroptical properties when compared to their monomeric counterpart. In this context, we report on the tetraphenylsilole and TPE derivatives with side-chains bearing an enantiomerically pure chiral units readily assembled into superhelical ropes upon aggregation, which displayed large CPL dissymmetry factors (g<sub>em</sub>) of –0.32 – a record for purely organic chiral materials.

2,3,4,5-Tetraarylsiloles are efficient solid-state luminescent materials with good electron-transporting ability. Substitution at the 2,5-positions of silole rings produce various outstanding functional materials that can be used as active layers in organic light-emitting diodes (OLEDs). In this work, two 2,5-dicarbazole-substitued siloles, (2-Cz)2MTPS and (3-Cz)2MTPS, are facilely synthesized and fully characterized. Their thermal, photophysical, electrochemical, and electroluminescent properties are investigated systematically. The results show that these 2,5-dicarbazole-functined siloles are thermally stable and feature aggregation-enhanced emission characteristics with high solid-state photoluminescence efficiencies. Nondoped OLEDs [ITO/N,N'-di(1-naphthyl)-N,N'-diphenyl-benzidine (NPB) (60 nm)/emitter (20 nm)/TPBi (40 nm)/LiF (1 nm)/Al (100 nm)] fabricated by adopting (2-Cz)2MTPS and (3-Cz)2MTPS as light-emitting layers exhibit good performances, with high luminance of 28240 cd m−2 and electroluminescence efficiency of 4.5 cd A−1.

The chiral nematic liquid crystal (N*-LC) has plenty of prospective applications in LC display (LCD) owing to the selective reflection and circular dichroism. The molecules in the N*-LC are aligned forming a helically twisted structure and the specific wavelength of incident light is reflected by the periodically varying refractive index in the N*-LC plane without the aid of a polarizer or color filter. However, N*-LC do not emit light which restricts its application in the dark environment. Moreover, the view angle of N*-LC display device was severe limited due to the strong viewing angle dependence of the structure color of the one dimensional photonic crystal of a N*-LC. In order to overcome these weaknesses, we have synthesized a luminescent liquid crystalline compound consisting of a tetraphenylethene (TPE) core, TPE-PPE, as a luminogen with mesogenic moieties. TPE-PPE exhibits both the aggregate-induced emission (AIE) and thermotropic liquid crystalline characteristics. By dissolving a little amount of TPE-PPE into N*-LC host, a circular polarized emission was obtained on the unidirectional orientated LC cell. Utilizing the circular polarized luminescence property of the LC mixture, we fabricated a photoluminescent liquid crystal display (PL-LCD) device which can work under both dark and sunlit conditions. This approach has simplified the device design, lowered the energy consumption and increased brightness and application of the LCD.

Simplifying the configurations of organic light-emitting diodes (OLEDs) without sacrificing device performances is of
high practical importance to shorten fabrication procedures and cut down cost. In view of this, organic active materials
for OLEDs are anticipated to possess multiple functions, including high solid-state emission efficiency, efficient hole- and/
or electron transport ability, etc. To realize this purpose, we designed a series of bifunctional materials consisting of
a silole core and electron-transporting functional groups, such as dimesitylboryl and diphenylphosphoryl groups. These
silole derivatives show aggregation-enhanced emission (AEE) characteristics and afford high emission efficiencies in the
solid films. The presence of these electron-withdrawing substituents lowers the LUMO energy levels as revealed by
cyclic voltammetry, and allows for efficient electron transport ability of the luminogens. The double-layer OLEDs
fabricated using these silole derivatives as light-emitting and electron-transporting layers simultaneously show good
electroluminescence performances, which are almost equal to those of triple-layer OLEDs with an additional electrontransporting
layer (TPBi), revealing that they are excellent n-type light emitters. These results demonstrate that the
combination of AEE-active luminogens with charge transport groups at molecular level is a promising design for
multifunctional solid-state light emitters.

Liquid crystal displays (LCDs) are widely used for diverse purposes in many aspects in daily life from handle personal devices to professional applications and large-panel LCD televisions. Since LCD is a passive emission display device, it usually shows narrow viewing angle and reduced brightness. Nowadays, LCDs with light-emitting properties is suggested as a less energy consuming displays. To date, fluorescent materials with dichroic properties and strong fluorescence emission are required. However, many molecular emitters, which are highly efficient in solution, will suffer from heavy aggregation-caused quenching (ACQ) effect in the aggregate state, which has greatly limited their applications. In order to overcome these weaknesses, we have designed and synthesized a novel luminescent liquid crystalline compound consisting of a tetraphenylethene (TPE) core, TPE-PPE, as a luminogen with mesogenic moieties. As a result, the TPE-PPE exhibits both the aggregate-induced emission (AIE) and thermotropic liquid crystalline characteristics. By dissolving 1 weight% (wt%) of TPE-PPE into the nematic LC host PA0182, a linearly polarized emission was obtained on the unidirectional orientated LC cell. The photoluminescence polarization ratio of the LC cell has reached to 4.16 between the directions perpendicular and parallel to the rubbing direction. Utilizing the emissive anisotropic TPE-PPE, we have fabricated the photoluminescent liquid crystal display (PL-LCD). This approach has simplified the device design, lowered the energy consumption and increased brightness of the LCD.

Luminescent materials have been widely applied in chemo- and bio-sensing applications because these luminescent materials offer high signal-to-background ratio, superior sensitivity and broad dynamic ranges in various detections. Conventional luminogens suffer from aggregation-caused quenching (ACQ) effect due to strong &pi;–&pi; stacking interaction upon aggregate formation of the luminogens with analytes. Such ACQ effect limits the scope of practical sensing applications. Luminogens with aggregation-induced emission (AIE) characteristics enjoy high emission efficiency in solid or aggregated state while they are non-emissive in solution. AIE luminogens (AIEgens) tackle the lethal problem of ACQ materials in the sensing applications. Siloles and tetraphenylethene (TPE) are archetypal AIE cores and possess advantages of facile synthesis and readily functionalization. AIEgens have been utilized to develop various fluorescent chemosensors. For example, hyperbranched AIE polymers with different topologies can be worked as turn-off explosive sensor with high sensitivity. The explosive detections can be done in solid film, which facilitates practical usage. The AIEgens can also be used as sensors for volatile organic compounds and metal ions through alternating fluorescence on/off mechanisms. Besides chemosensor, the AIEgens have been applied in the fields of biology. Water-soluble AIEgens have been developed for quantifying nucleic acids and proteins. They can serve as bioprobes for real-time monitoring and studying the kinetic of protein conformational changes, making them promising for diagnostic and therapeutic applications. These demonstrations significantly expand the scope of analysis applications of AIEgens and offer new strategies to the design of new fluorescent chemo- and bio-sensors.

Fluorescence techniques have been extensively employed to develop non-invasive methodologies for tracking and understanding complex biological processes both in vitro and in vivo, which is of high importance in modern life science research. Among a variety of fluorescent probes, inorganic semiconductor quantum dots (QDs) have shown advantages in terms of better photostability, larger Stokes shift and more feasible surface functionalization. However, their intrinsic toxic heavy metal components and unstable fluorescence at low pH greatly impede the applications of QDs in in vivo studies. In this work, we developed novel fluorescent probes that can outperform currently available QD based probes in practice. Using conjugated oligomer with aggregation-induced emission characteristics as the fluorescent domain and biocompatible lipid-PEG derivatives as the encapsulation matrix, the obtained organic dots have shown higher brightness, better stability in biological medium and comparable size and photostability as compared to their counterparts of inorganic QDs. More importantly, unlike QD-based probes, the organic fluorescent dots do not blink, and also do not contain heavy metal ions that could be potentially toxic when applied for living biosubstrates. Upon surface functionalization with a cell-penetrating peptide, the organic dots greatly outperform inorganic quantum dots in both in vitro and in vivo long-term cell tracing studies, which will be beneficial to answer crucial questions in stem cell/immune cell therapies. Considering the customized fluorescent properties and surface functionalities of the organic dots, a series of biocompatible organic dots will be developed to serve as a promising platform for multifarious bioimaging tasks in future.

Biphenyl-containing diazides and diynes carrying tetraphenylethylene units are designed and synthesized. Their "click"
polymerizations are initiated by Cu(PPh3)3Br in THF or DMF, affording soluble, regioregular polytriazoles in high yields
(up to 94.8%) with narrow molecular weight distributions. The structures and properties of the polymers are evaluated
and characterized by IR, NMR, UV, PL, TGA, DSC, POM and XRD measurements. All the polymers are almost
nonluminescent when dissolved in solutions but become highly emissive when aggregated in poor solvents or fabricated
as thin films in the solid state, displaying a novel phenomenon of aggregation-induced emission. The photophysical
properties of the polymers are sensitive to their molecular structures and their solid-state quantum yields decrease with
an increase in the spacer length. All the polymers enjoy high thermal stability, with 5% weight loss occurring at
temperatures up to 406 &deg;C. They are mesomorphic. While polymers with rigid main chains exhibit nematicity, those with
longer spacer lengths show better mesogenic packing and hence form sematic phases at higher temperatures.

Triphenylene-containing poly(1-decyne)s with different alkyl chain lengths are synthesized and the effects of the
structural variables on their mesomorphic properties are investigated. The monomers
[HC&equiv;C(CH<sub>2</sub>)<sub>8</sub>CO<sub>2</sub>C<sub>18</sub>H<sub>6</sub>(OC<sub>m</sub><sub>H2m+1</sub>)<sub>5</sub>; m = 4-9] are prepared by consecutive etherization, coupling, and esterification
reactions. The monomers form columnar phases at room temperature. The polymerizations of the monomers are
effected by [Rh(nbd)Cl]<sub>2</sub>, producing soluble polymers in high yields (up to 84%). The structures and properties of the
polymers are characterized and evaluated by IR, NMR, TGA, DSC, POM, and XRD analyses. All the polymers are
thermally stable, losing little of their weights when heated to 300&deg;C. The isotropization temperature of the polymers
increases initially with the length of alkyl chain but decreases on further extension. Whilst the polymers with shorter and
longer alkyl chain lengths adopt a homogeneous hexagonal columnar structure, those with intermediate ones form
mesophases with mixed structures.

A group of organic chromophoric molecules including siloles, pyrans, tetraphenylethylenes and fulvenes, are designed
and synthesized. Light emissions of conventional luminescent materials are often quenched by aggregate formation.
These molecules, however, become stronger luminophors when aggregated although they are practically nonemissive in
their dilute solutions. By varying their packing structures in the aggregation states, emission color ranging from blue to
red can be achieved. The emission of fulvenes can also be controlled by changing their morphology. While they emit a
faint light in the amorphous state, their crystal forms are strongly luminescent. Intermolecular interaction or restriction of
intramolecular rotation in different states may be responsible for such behaviors. Thanks to such effects, the molecules
can be employed as sensors for the detection of explosives, organic solvent vapors, solution pH, and biomacromolecules.
Further modification of their structures by molecular engineering endeavors may generate materials that can find an
array of applications in optical display systems and as biological probes.

New chromophoric molecules of 1,1-di(thiophen-2-yl)-2,3,4,5-tetraphenyl-silole (T<sub>2</sub>TPS), 9-(diphenylmethylene)-9<i>H</i>-fluorene (DPMF), and tetraphenyletheneare (TPE) are designed and synthesized. When molecularly dissolved in common organic solvents, the molecules are practically nonemissive. Addition of poor solvents induces the molecules to aggregate, which turns the emission "on" and boosts their luminescence efficiencies dramatically ("aggregation-induced emission" or AIE). The photoluminescence (PL) of T<sub>2</sub>TPS and TPE layers adsorbed on the TLC plates can be turned "off" and "on" continuously and reversibly by solvent exposure and evaporation. Transformation from amorphous phase to crystalline structure blue-shifts the PL spectrum of T<sub>2</sub>TPS and enhances its intensity. A light-emitting devices (LEDs) device based on TPE is fabricated, which emits a blue light of 447 nm with a low turn-on voltage of 2.9 V.

Poly(phenylacetylene)s and poly(1-alkyne)s containing chiral sterol pendant groups with molecular structures of
-[HC=C-C<sub>6</sub>H<sub>4</sub>-CO<sub>2</sub>-R]<sub>n</sub>-, -[HC=C-C<sub>6</sub>H<sub>4</sub>-O(CH<sub>2</sub>)<sub>10</sub>-CO<sub>2</sub>-R]<sub>n</sub>- and -[HC=C(CH<sub>2</sub>) <sub>m</sub>CO<sub>2</sub>-R]<sub>n</sub>-, (where R =
cholesterol, stigmasterol, ergosterol and m = 2, 3, 8} are designed and synthesized. The monomers are prepared by esterifications of acetylenic acids with cholesterol, stigmasterol, and ergosterol and exhibit cholestericity at high
temperatures. Polymerizations of the monomers are effected by WCl<sub>6</sub>-Ph<sub>4</sub>Sn, MoCl<sub>5</sub>-Ph<sub>4</sub>Sn, and organorhodium
catalysts, giving high molecular weight (M<sub>w</sub> up to 8.0 × 10<sup>5</sup>) polymers in high yields (up to 99%). The structures and
properties of the polymers are characterized and evaluated by IR, NMR, TGA, DSC, POM, X-ray, UV, and CD
analyses. All the polymers are thermally stable (greater than or equal to 300 °C). Polymers with long flexible alkyl chains form smectic and
cholesteric phases at elevated temperatures. With an increase in the spacer length in poly(1-alkyne)s, the packing
arrangements of the mesogenic pendants in the mesophases change from bilayer or mixed mono- and bilayer into
homogeneous monolayer structures. Few poly(phenylacetylene)s show CD bands in the absorption region of the
polyacetylene backbones, revealing that the main chains are helically rotating with a preferred screw sense.

Azo-functionalized hyperbranched polymers <b>1</b> and <b>2</b>, and linear polyacetylene <b>3 </b>are synthesized by palladium-catalyzed
coupling of triiodoarenes with a diethynylazobenzene, and post functionalization, respectively. These polymers are
soluble, film-forming, and morphologically stable (<i>T</i><sub>g</sub> > 180 <sup>o</sup>C). The poled polymer films of <b>1</b> and <b>2</b> exhibit high
second-harmonic generation coefficients (<i>d</i><sub>33</sub> up to 177 pm/V), thanks to the chromophore-separation and site-isolation
effects of hyperbranched architectural structure of the polymers in the three-dimensional space. The poled film of
polymer <b>3</b> shows the trade-off of nonlinearity-transparency-orientation thermal stability. The poled films are all
orientationally and thermally stable due to the facile cross-linking of the multiple acetylenic triple bonds in the
hyperbranched polymer and the rigid backbone in the linear polyacetylene, respectively.

Nonlinear optical (NLO) processes in pi-electron organic and polymer systems have attracted considerable interest because their understanding has led onto many compelling technological promise as well as the discovery of new phenomena, new theoretical insights, and new materials and devices. In recent years, as the field has progressed toward technological applications, the main issues have focused on high-performance materials that comply with device manufacturing and end-use conditions. New challenges in materials synthesis are being presented. In has now been demonstrated on pilot plant scales that high-performance electro-optic polymer thin films can be routinely used in optoelectronic integrated circuit fabrication in existing microelectronic device manufacturing facilities. The key steps are standard, including spin coating, photolithography, etching, metallization, and multilayer assembly. Nanocrystal quantum dots (QDs) have been incorporated into various NLO polymers and the optical properties of the nanocomposite films have been studied by femtosecond laser Z-scan instrumentation. Nanodevices have been fabricated by UV-assisted imprinting fabrication techniques. Photonic devices based on nanomaterials and ring resonators e.g., optical switches and dispersion compensators, are discussed.

A series of new disubstituted liquid crystalline polyacetylenes (LCPAs) with general molecular structures of -{(R)C=C[(CH<sub>2</sub>)<sub><i>m</i></sub>-Mes]}<i><sub>n</sub></i>- and -[(C<sub>6</sub>H<sub>13</sub>)C=C(C<sub>6</sub>H<sub>4</sub>-Mes)]<sub><i>n</i></sub>- (R = CH<sub>3</sub>, C<sub>6</sub>H<sub>5</sub>, <i>m</i> = 3, 4, 9, Mes = mesogen) have been designed and synthesized. All the LCPAs are thermally stable and do not loss their weights when heated to a temperature as high as ~400&deg;C. While a few polymers exhibit nematicity, most of them form enantiotropic S<sub>A</sub> phase of monolayer structure. Upon photoexcitation, the polymers emit intense UV and blue lights with quantum yield up to 81%. Multilayer light-emitting diodes with a device configuration of ITO/PVK/PA/LiF/Al are constructed, which emits blue light with maximum luminance and external quantum efficiency of 119 cd/m<sup>2</sup> and 0.12%, respectively.

Mesomorphic and luminescent poly(propiolates) with different skeleton structures (-{(R)CequalsC[CO<SUB>2</SUB>(CH<SUB>2</SUB>)<SUB>6</SUB>OCO-Biph- OC<SUB>7</SUB>H<SUB>15</SUB>]}<SUB>n</SUB>-; R equals H (1), CH<SUB>3</SUB> (2), C<SUB>6</SUB>H<SUB>5</SUB> (3), Biph equals biphenylyl} are synthesized. The backbone absorption in 2 and 3 are weak but upon photoexcitation, the polymers emit strong violet light of 369 nm, whose intensities are higher than that from poly(l-phenyl-l-octyne), a well-known highly-fluorescent polyacetylene. The main chain of 3 absorbs strongly at 380 nm, and the polymer is completely nonluminescent. All the polymers are thermally stable and form enantiotropic monolayer SmA phase, with 1 adopting well-ordered packing arrangements.

The photo-aligning materials based on azodye layers are proposed. The azodye aligning layers enable (i) high order parameter; (ii) excellent alignment quality of LCD with a high contrast ratio; (iii) temperature stability, suitable for LCD manufacturing; (iv) perfect adhesion and high voltage holding ratio due to the specific molecular groups (v) pretilt angle generation. The azodye layers can be used to fabricate thin internal patterned (pixelated) polarizers with different local orientations of the absorption axis and/or absorption colors. Our new methods allow to produce defect-free highly uniform alignment of lyotropic LC or iodine-doped azodye layers themselves with a fine resolution of the polarization pattern. The photo-aligned internal polarizers are cost-effective and enable new LCDs with excellent electro-optical response, including good viewing angles and high brightness. We prepared an internal phase retarder using UV-cured photo-polymerized material. 4-(6- acryloyloxyhexyloxy) benzoic acid had been synthesized and the synthesis procedure was modified for a better yield. We had shown that by applying an electric or magnetic field, the director deformation of the liquid crystalline monomer could be in-situ UV-cured for the optimal phase compensation generation.

Development of advanced polymeric materials with both liquid crystallinity and light emissivity is of scientific interest and technological importance. In this study, we studied light emission from tetrahydrofuran solutions of a liquid crystalline polyacetylene, poly(11-{[(4'-heptoxy-4- biphenylyl)carbonyl]oxy}-1-undecyne), in the electrical field. The field exerts little effect on the photoluminescence of the polymer solution with a low concentration (0.10 mM). The photoluminescence of a concentrated solution (11.3 mM) is, however, noticeably quenched under an electrical field with a field strength of &gt; 300 kV/m. When the field strength is increased to &gt;= 367 kV/m, the bimodal emission spectrum of the solution changes to a monomodal one. Thus, both the emission intensity and spectral profile of the luminescence of the concentrated solution can be tuned by the electrical field, which is probably caused by the aggregate dissociation and mesogen realignment induced by the external stimulus.

We have studied the electronic structure, absorption, and photoluminescence of poly(1-phenyl-2-alkynes) - [C<SUB>6</SUB>H<SUB>5</SUB>)C- C(C<SUB>m</SUB>H<SUB>2m+1</SUB>)]<SUB>n</SUB>-(m = 1, 2), poly(phenylacetylene)-[HC=C(C<SUB>6</SUB>H<SUB>5</SUB>]<SUB>n</SUB>- and its derivatives -[HC=C(C<SUB>6</SUB>H<SUB>4</SUB>-p-R]<SUB>n</SUB> with various non- liquid crystal ring substitutes. For poly(1-phenyl-2- alkynes), the PL efficiency is very sensitive to the molecular structure of the alkyl pendant and can be enhanced up to 50 times as the alkyl side-chain increases in length. But for poly(phenylacetylenes), their luminescent efficiency can be improved several times only as the tail becomes bulky. Regardless of the types of the pendants, the emission color of the polymers is pineed at ~450 nm (2.7eV). The band structure of the polymers, which has been calculated using extended Huckel tight-binding method, is essentially an ensemble of the backbone (extended states) and the pendants (localized states), and the processes of optical absorption and blue emission are confined in the directly attached aromatic ring. The interaction between the pheny chromophore and its nearest neighbors is of vital importance in improving the emission efficiency. Although the band gap of the backbone can be enlarged by the pendant, its (pi) - (pi) <SUP>*</SUP> interband transistion is insignificant for the blue emission.

A large number (more than 20 different kinds) of new polyacetylenes with general molecular structures of -[HC equals C(C<SUB>6</SUB>H<SUB>4</SUB>-mesogen)]<SUB>p</SUB>- [poly(arylacetylene) type] and -{HC equals C[(CH<SUB>2</SUB>)<SUB>n</SUB>-mesogen]}<SUB>p</SUB>- [poly(alkylacetylene) type] are designed and synthesized. Pendant interaction and backbone rigidity in the polymers are tuned through systematic molecular engineering endeavor, and liquid crystalline polyacetylenes (LCPAs) with novel mesomorphic, optical, and electronic properties are successfully developed. The rigid polyacetylene backbones enable ready alignments of the LCPA molecules by simple mechanical perturbations. Upon photoexcitation, the LCPAs with the poly(alkylacetylene) skeleton structure emit strong blue light clearly observable by naked eyes under normal room illumination conditions. The shape and position of the emission peaks and the color of the emitted light can be manipulated by the application of external electrical fields. The LCPAs exhibit excellent intrinsic photoconductivity in the visible spectral region in the undoped (pure) states, and doping with electron acceptor/donor further increases the photoconduction efficiency of the LCPAs.

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Journal of Applied Remote SensingJournal of Astronomical Telescopes Instruments and SystemsJournal of Biomedical OpticsJournal of Electronic ImagingJournal of Medical ImagingJournal of Micro/Nanolithography, MEMS, and MOEMSJournal of NanophotonicsJournal of Photonics for EnergyNeurophotonicsOptical EngineeringSPIE Reviews